bugtool: Collect bond state information from ovs.

This is an enhancement in bugtool archive output to determine the bond
state information. It is implemented as a plugin which internally calls
"ovs-appctl bond/show" command to get bond state.

Feature #11283.
Signed-off-by: Arun Sharma <arun.sharma@calsoftinc.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>